com.antelmann.calendar
Class AtomicClock

java.lang.Object
  com.antelmann.calendar.AtomicClock

All Implemented Interfaces:

TimeSystem

public class AtomicClock
extends Object
implements TimeSystem

uses the Network Time Protocol (NTP). This simple implementation is based on a single server.

Author:

Holger Antelmann

See Also:

NTPServer, AtomicTime

Field Summary

static int	DEFAULT_NTP_PORT 37
static String	DEFAULT_NTP_SERVER time-b.nist.gov
protected static String[]	knownServerList a small list of known servers besides the default one

Fields inherited from interface com.antelmann.calendar.TimeSystem

systemTime

Constructor Summary

AtomicClock()
uses time-b.nist.gov

AtomicClock(String serverName)
uses the standard port 37

AtomicClock(String serverName, int port)

Method Summary

int	adjustDelta() adjusts the delta value used for getTime() through using the server time
TimerTask	createTimerTask(Logger logger) creates a TimerTask that will adjust the delta and log the result to the given logger.
int	currentDelta() returns the current difference between system time and atomic time in milliseconds.
long	currentTimeMillis() returns the system time adjusted by the delta value.
long	currentTimeMillisOnline() returns the current time in the current locale retrieved directly from the server.
Calendar	getCalendar() returns the calendar used to localize the time
int	getDelta() returns the stored difference between system time and atomic time in milliseconds.
static String[]	getKnownServerList()
long	getLastDeltaAdjustmentTime() returns the system time when adjustDelta() has been successfully called last time.
int	getPort()
String	getServer()
int	getTimeout()
static void	main(String[] args) console based demo app displaying the delta between the system time and the server
protected int	secondsSince1900() returns the raw int directly from the server
void	setDelta(int delta) manually sets the value used to adjust system time
static void	setKnownServerList(String[] newList)
void	setPort(int port)
void	setServer(String serverName)
void	setTimeout(int timeout)
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

DEFAULT_NTP_SERVER

public static final String DEFAULT_NTP_SERVER

time-b.nist.gov

See Also:

Constant Field Values

DEFAULT_NTP_PORT

public static final int DEFAULT_NTP_PORT

37

See Also:

Constant Field Values

knownServerList

protected static String[] knownServerList

a small list of known servers besides the default one

Constructor Detail

AtomicClock

public AtomicClock()

uses time-b.nist.gov

AtomicClock

public AtomicClock(String serverName)

uses the standard port 37

AtomicClock

public AtomicClock(String serverName,
                   int port)

Method Detail

getKnownServerList

public static String[] getKnownServerList()

setKnownServerList

public static void setKnownServerList(String[] newList)

getServer

public String getServer()

setServer

public void setServer(String serverName)

getPort

public int getPort()

setPort

public void setPort(int port)

setTimeout

public void setTimeout(int timeout)

getTimeout

public int getTimeout()

getCalendar

public Calendar getCalendar()

returns the calendar used to localize the time

currentTimeMillis

public long currentTimeMillis()

returns the system time adjusted by the delta value. This is generally the prooper method to be called by the application.

Specified by:

currentTimeMillis in interface TimeSystem

Returns:

the difference, measured in milliseconds, between the current time and midnight, January 1, 1970 UTC.

secondsSince1900

protected int secondsSince1900()
                        throws IOException

returns the raw int directly from the server

Throws:

IOException

currentTimeMillisOnline

public long currentTimeMillisOnline()
                             throws IOException

returns the current time in the current locale retrieved directly from the server. Calling this method does not affect the delta value of this instance.

Throws:

IOException

currentDelta

public int currentDelta()
                 throws IOException

returns the current difference between system time and atomic time in milliseconds. A negative number indicates that the system clock is behind. Calling this method does not affect the delta value of this instance.

Throws:

IOException

getDelta

public int getDelta()

returns the stored difference between system time and atomic time in milliseconds. A negative number indicates that the system clock is behind.

See Also:

adjustDelta(), setDelta(int)

setDelta

public void setDelta(int delta)

manually sets the value used to adjust system time

See Also:

adjustDelta()

getLastDeltaAdjustmentTime

public long getLastDeltaAdjustmentTime()

returns the system time when adjustDelta() has been successfully called last time. If no sucessful adjustment has taken place, yet, the method returns 0.

See Also:

adjustDelta()

adjustDelta

public int adjustDelta()
                throws IOException

adjusts the delta value used for getTime() through using the server time

Throws:

IOException

See Also:

currentTimeMillis(), getDelta(), setDelta(int), getLastDeltaAdjustmentTime()

createTimerTask

public TimerTask createTimerTask(Logger logger)

creates a TimerTask that will adjust the delta and log the result to the given logger. The logger may be null.

See Also:

adjustDelta(), Timer

toString

public String toString()

Overrides:

toString in class Object

main

public static void main(String[] args)
                 throws IOException

console based demo app displaying the delta between the system time and the server

Throws:

IOException